A Review of the Pennsylvania Phosphorus Index ... - PennFuture

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It is worth noting that the PSC Book values for the various manures has also changed fromVersion 1 to Version 2 (Table 2). The poultry categories as well as liquid dairy that were 0.9 inVersion 1 were reduced to 0.8 in Version 2. The biosolids catagories which had PSC’s of 0.3 inVersion 1, were all increased to 0.4 in Version 2. A PSC for horse manure is also added toVersion 2.Table 2. Organic phosphorus source availability coefficientsOrganic Source Version 1 PSC* Version 2 PSC +Swine slurry 1.0 1.0Poultry Broiler 0.8 0.8 Layer 0.9 0.8 Turkey 0.9 0.8 Duck 0.9 0.8Dairy Liquid 0.9 0.8 Bedded pack 0.8 0.8 Beef 0.8 0.8Horse Not Provided 0.8Alum treated manure 0.5Biosolids Biological nutrient removal 0.8 0.8 Alkaline stabilized 0.4 0.4 Conventionally stabilized 0.3 0.4 Composted 0.3 0.4 Heat-dried 0.2 0.4 Advanced-alkaline stabilized 0.2 0.4*Beegle et al 2006+Beegle et al 2009The Influence of Phosphorus Solubility Coefficients on Phosphorus Index ValuesGiven the lack of data on actual WEP-based PSC values, a set of hypothetical calculationsintended to show the resulting P-Index values at PSC values across the range of possibilities wasconducted. Nutrient management data from the Appendix within Kogelmann et al. (2004) wererecalculated with PSC values ranging from Book values to o.1. All the examples presented inKogelmann et al (2004) are from livestock operations in Lancaster and Snyder Counties andwere calculated with Book PSC values before any modifications in application rates or methodsor BMPs were considered. Specifically, in the hypothetical calculations, the PSC values neededto reduce P-Index values from one category to a lower P-Index category were determined andthe quantity of change in both the PSC and resulting P-Index from the original values wasPage 7
plotted (Figure 2). By lowering the P-Index ranking categories, P application restrictions wouldbe reduced or removed. For examples initially in the Very High P-Index category, PSC valuesnecessary to reduce the P-Index ranking to High and Medium were determined with thefollowing exceptions. In one case, the minimum PSC (0.1) did not reduce the P-Index categoryfrom the Very High ranking. In 3 other cases, the minimum PSC only lowered the P-Index fromthe Very High to the High ranking. For examples with P-Index values in the High rank, PSCvalues necessary to reduce the P-Index to Medium were calculated.Quantity of P-Index change120100806040200P-Index change vs. PSCchange0 0.2 0.4 0.6 0.8 1y = 83.143x + 0.0752R² = 0.5791PI changeQuantity of PSC reduction from "Book value"Linear (PI change)Figure 2. Change of P-Index (PI) versus the reduction in PSC from “Book value.” Data adaptedfrom Kogelmann et al. 2004.Based upon this analysis, the reduction in PSC values was significantly correlated with thereductions in the P-Index ratings (P>.001; R2 = 0.58.). For each reduction in PSC of 0.1, acorresponding reduction of about 8 P-Index units is predicted, on average. This relationshipseems especially well correlated for reductions in PSC values from Book values of less than 0.3units.The increase variability in the relationship between PSC reductions and change in P-Indices asthe level of PSC reduction increases may be related to the variability in the influence of thesource and transport terms. Kogelmann et al (2004) found that about 50% of the P restrictionson farms in Lancaster County were due to high P sources, either from high soil tests or highmanure P application rates. Transport factors were the primary concern in 21% of the cases andfor the remaindering 29%, both source and transport contributed equally. In Snyder County,transport factors and source factors were found to be about equal, with transport factorsshowing a slightly higher influence on P-Index rankings.Page 8
Page 1 and 2: A Review of thePennsylvaniaPhosphor
Page 3 and 4: The P-Index source factor uses a Me
Page 5 and 6: 1:100 extraction ratio (i.e. 2.5 g
Page 7: Table 1. Conditions assumed in exam
Page 11 and 12: and Mehlich-3 extractable soil P co
Page 13 and 14: overestimation is incorporated into
Page 15 and 16: 4. Require BMPs to reduce P loss fr

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